Explorer.exe starts very slow after Windows update build 16299

My Acer laptop reacts very slow on starting explorer.exe. After about 1 minute the explorer starts.

I contacted Microsoft and they told me that my laptop model isn't compatible with the latest Windows 10 build. They couldn't do anything for me and advised me to contact Acer support, because they thought it was a driver problem.

Acer support told me that I had to go back to Windows 8.1 to solve all my problems. I don't think that's a realistic option for me. Everything works fine except explorer.exe.
Acer advised me to contact a local windows expert, but I don't know one, so I post this message here.

Windows 10 build 16299
Acer Aspire V3-771G-73638G50MAII
Intel Core I7-3632QM 2.20GHz
Intel HD Graphics 4000
NVidia GeForce 710M
12 GB memory

Who can help me?

"They couldn't do anything for me and advised me to contact Acer support, because they thought it was a driver problem. .... after Windows update 10 build 16299"

RUBBISH ! Your specs indicate that you have an upper end, though older, computer. Explorer is a basic part of the OS, however. Was this an Update to or was your device UPGRADED to 16299 from a previous ver ? What's the current version ? Hit Win+R, type winver and post 16299 Build #.

An easy thing to do is an In-place Repair Upgrade - Repair Install Windows 10 with an In-place Upgrade
Use option 4: download the MCT tool and use it to create an ISO on your desktop, Mount/Open and run setup exe (faster if you opt out of Updates). This will reinstall the base version of Fall creators (16299). See the tutorial video first, beginning at 3:24 mark, if you feel uncomfortable, at all, just diving in. Post your progress.